Finite Math and Applied Calculus (6th Edition)

Published by Brooks Cole
ISBN 10: 1133607705
ISBN 13: 978-1-13360-770-0

Chapter 13 - Section 13.2 - Substitution - Exercises - Page 971: 44

Answer

$\ln|2x-1|-\ln|x|+C$

Work Step by Step

$I=\displaystyle \int\frac{1}{x^{2}(2-1/x)}dx$ We need a substitution such that $du$ has $x^{2}$ in the denominator $\left[\begin{array}{llll} u & =2-\frac{1}{x}=2-x^{-1} & & \\ & & & \\ du & =x^{-2}dx =\dfrac{dx}{x^{2}} & \Rightarrow & \dfrac{dx}{x^{2}}=du \end{array}\right]$ $I=\displaystyle \int(\frac{1}{2-1/x})(\frac{dx}{x^{2}})=\quad $ apply the substitution $= \displaystyle \int u^{-1}du$ special case of the power rule, $n=-1,$ $=\ln|u|+C$ bring back the variable $x$ $=\displaystyle \ln|2-\frac{1}{x}|+C$ $=\displaystyle \ln|\frac{2x-1}{x}|+C$ = $\ln|2x-1|-\ln|x|+C$
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